Ceiling fan with high efficiency ceiling fan blades

ABSTRACT

A ceiling fan including a motor having a rotatable rotor, a plurality of ceiling fans blades having a thickness, the blades connected to the rotor to rotate therewith and each of the ceiling fan blades comprising a thin edge along its leading edge that is thinner than the thickness of the ceiling fan blade to present less resistance and produce less turbulence and achieve high efficiencies.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to ceiling fans. More particularly, thisinvention relates to ceiling fan blades having a high-efficiency design.

2. Description of the Background Art

Presently, there exist numerous types of ceiling fans designed to besuspended from a ceiling for circulating air flow within the room.Typically, ceiling fans comprise a plurality of ceiling fan blades whichare operatively connected to an electric motor for rotating the fanblades to produce the desired air flow. The components of the ceilingfan, particularly the ceiling fan blades, are designed to optimize theamount of air flow being circulated per watt of energy consumed tothereby achieve high efficiencies.

The fan blades constitute one component of a ceiling fan which is animportant factor in achieving high efficiencies. Ceiling fan bladescommonly include an elongated planar or curvilinear structure having aproximal or root end which is coupled to a fan blade bracket which is,in turn, coupled to the rotor of the electric motor. The elongatedplanar fan blade is positioned by the fan blade bracket at an optimalangle (e.g., 11 to 17 degrees) to circulate air flow at highefficiencies.

Elongated planar ceiling fan blades are commonly manufactured of amedium-density fiber (“MDF”), laminated plywood, carved wood or plastic.More particularly, MDF fan blades are manufactured from large sheets ofMDF wood that are pressed together to the desired thickness, typically5.5 millimeters. The surface of the MDF sheets are protected by vinylsheets which are overlaid onto the MDF sheets and glued to the surfacethereof (upper and lower) to form a watertight seal therewith. The MDFsheets are then positioned within a cutting machine which cuts out theindividual ceiling fan blades from the MDF sheet in the desired pattern.The leading and trailing edges of the fresh-cut ceiling fan blade arethen routed and sanded to produce a round edge with the vinyl extendingthereto. The rounded edge of the ceiling fan blade is then painted witha waterproof paint to seal the rounded edge so that moisture cannotpenetrate into the rounded edge and seep underneath the vinyl sheet.Warpage of the fan blade, which would otherwise deteriorate the fanblade causing it to wobble, is therefore minimized.

Similar to MDF blades, plywood blades have been used for many years.Unlike MDF blades, plywood blades are typically lighter in weight,stronger and less likely to warp due to their cross grain constructionand multiple plies. More particularly, conventional plywood commonlyincludes three plies of cross grain planar sheets of wood. During themanufacture of plywood fan blades, two sheets of the three ply plywoodare glued to form a plywood sheet having six plies. The sheet of plywoodis often covered with a vinyl material (upper and lower) that mayinclude a solid color or a wood grain appearance. Alternatively, one orboth sides of the plywood may be covered by a light colored paper. As inthe case of manufacturing the MDF fan blades, the plywood sheets arethen cut to the desired blade shape and their edges are routed andsanded to have a rounded edge. The rounded edges are then painted with awaterproof sealant to preclude any ingress of moisture that mightotherwise cause delamination of the plywood.

Plastic fan blades are most commonly used for outdoor fans anddecorative fans, and may include a simulated wicker or rattanappearance. Plastic fan blades offer the advantage of being formed intocurvilinear configurations, such as those shown in U.S. Pat. Nos.6,659,721 and 6,309,541, the disclosures of which are herebyincorporated by reference herein. Unfortunately, however, since plasticis typically heavier than plywood or MDF, plastic fan blades result inhigher resistance to the electric motor thereby necessitating increasedtorque. Moreover, due to gravity acting on the blades, the plasticblades must be thick enough to preclude them from warping or droopingover time. Consequently, plastic blades are often significantly thickerthan their plywood or MDF counterparts. To reduce the likelihood ofdrooping, plastic blades may include a slightly raised center rib to addlongitudinal strength.

The rounded edges of MDF blades, plywood blades and plastic bladespresent a thick edge. Consumers view the thick edge with appreciationbecause the thick rounded edge gives the ceiling fan an appearance ofbetter quality. Unfortunately, however, the thick rounded edge ofconventional fan blades produce a significant air resistance andturbulence as the ceiling fan blades are rotated through the air tocause the desired air flow. The increased resistance and turbulencealong the leading edge of the thick rounded leading edge of the fanblade appreciably reduces the efficiency of the ceiling fan. In the caseof the thicker plastic blades, even greater inefficiencies are oftenexperienced.

Efforts to produce thinner blades that would correspondingly havethinner rounded edges, have met with little success since thinner bladesdo not have the necessary strength to function properly during continueduse without droopage. Moreover, prior art techniques for “beveling” theleading edge of a ceiling fan blade, such as taught by Taiwan PatentApplication 79200819, filed Jan. 22, 1990, the disclosure of which ishereby incorporated by reference herein, have not met with anycommercial success. More particularly, beveling the leading edge of aceiling fan blade such as taught by the Taiwanese patent applicationproduces a relatively sharp knife edge that creates a hazardouscondition in the event a person's hand or other object is moved into thepath of the spinning fan blades. Indeed, industry safety regulationsapplicable to ceiling fans mandate that the leading edge of the fanblade must be greater than 3.30 millimeters thick so as to reduce thelikelihood of injury should a person's hand or other object move intothe path of the rotating fan blades.

As noted above, recent improvements to ceiling fan blade designs havebeen achieved by manufacturing the ceiling fan blades in a longitudinalcurvilinear configuration as opposed to a longitudinal planarconfiguration. The curvilinear blade commonly includes a substantialangle (e.g. 30 degrees) at its root or proximal end connected to theceiling fan blade bracket which gradually tapers to the more traditionalangle of 11 to 17 degrees toward the distal end or tip of the fan blade.The airfoil configuration imitates the airfoil wing of an airplane forincreased “lift” correspondingly to increase air flow when the airfoilconfiguration is employed as a ceiling fan blade. This curvilinearconfiguration increases air flow at the center portion of the fan thanwhat can be achieved by using planar fan blades. Unfortunately, likeplanar fan blades, curvilinear fan blades still produce appreciableresistance and turbulence along their leading edges.

There presently exists a need in the ceiling fan industry for improvedceiling fan blades that operate safely to achieve high efficiencies.Therefore, it is an object of this invention to provide an improvementwhich overcomes the aforementioned inadequacies of the prior art devicesand provides an improvement which is a significant contribution to theadvancement of the ceiling fan blade art.

Another object of this invention is to provide a ceiling fan having ahigh efficiency fan blade that meets industry-wide safety standards.

The foregoing has outlined some of the pertinent objects of theinvention. These objects should be construed to be merely illustrativeof some of the more prominent features and applications of the intendedinvention. Many other beneficial results can be attained by applying thedisclosed invention in a different manner or modifying the inventionwithin the scope of the disclosure. Accordingly, other objects and afuller understanding of the invention may be had by referring to thesummary of the invention and the detailed description of the preferredembodiment in addition to the scope of the invention defined by theclaims taken in conjunction with the accompanying drawings.

SUMMARY OF THE INVENTION

For the purpose of summarizing this invention, this invention comprisesa ceiling fan having high efficiency fan blades. More particularly,several embodiments of the high efficiency fan blades of the inventioneach comprise a thin-edge configuration that effectively reducesthickness of the leading edge of prior art ceiling fan blades such thatthe thinner leading edge of the invention presents less resistance andproduces less turbulence than thicker prior art fan blade edges. Thethin-edge fan blades of the invention therefore result in highefficiencies.

More particularly, one embodiment of the high efficiency ceiling fanblades of the invention comprises a generally planar or curvilinearelongated configuration (MDF, plywood, carved wood or plastic) with areduced-thickness or thin leading edge. In one variation, the “thin”leading edge achieves a leading edge thickness equal to or appreciablygreater than the industry standard minimum thickness. The thin leadingedge then gradually tapers or steps into the thickness of a conventionalMDF, plywood or plastic blade. The thin leading edge is preferablycentered relative to the usual thickness of the blade. Alternatively,however, the reduced-thickness edge may be positioned at one surface ofthe fan blade, preferably the lower surface.

Importantly, the thin leading edge of the invention is easily adapted toall types of ceiling fan blades that are currently being manufactured.For example, in the case of plastic fan blades, the thin edge design ofthe invention may be easily injection molded. In the case of plywood fanblades and MDF fan blades, the edge of the fan blade may be easilyrouted to the desired thin edge design and then sealed with a waterproofsealer painted onto the exposed edges.

In another embodiment of the high efficiency ceiling fan blades of theinvention, the upper surface of the ceiling fan blades may comprise agenerally apex configuration defined by two planar surfaces formed at anangle leading from the opposing thin leading edges across the width ofthe fan blade to form an apex along a center line of the fan blade.Importantly, the thickness of the fan blade at the thin leading edgescomprises a reduced thickness which is equal to or appreciably greaterthan the minimum thickness mandated by applicable ceiling fan safetyregulations. It is noted that the thin leading edge of this embodimentof the invention is contemplated to be principally formed by plasticinjection molding or through carved fan blades due to the anglesinvolved that could not typically be achieved through the use oflaminated plywood or MDF. Indeed, this second embodiment is particularlydesirable for implementation with decorative plywood or carved wood fanblades that would normally require significant sanding or carving toachieve the desired decorative designs. Moreover, the apex configurationprovides strength along the longitudinal length of the fan blade therebyreducing the likelihood of drooping due to gravity over extended periodsof non-use.

The foregoing has outlined rather broadly the more pertinent andimportant features of the present invention in order that the detaileddescription of the invention that follows may be better understood sothat the present contribution to the art can be more fully appreciated.Additional features of the invention will be described hereinafter whichform the subject of the claims of the invention. It should beappreciated by those skilled in the art that the conception and thespecific embodiment disclosed may be readily utilized as a basis formodifying or designing other structures for carrying out the samepurposes of the present invention. It should also be realized by thoseskilled in the art that such equivalent constructions do not depart fromthe spirit and scope of the invention as set forth in the appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the nature and objects of the invention,reference should be had to the following detailed description taken inconnection with the accompanying drawings in which:

FIG. 1 is a side elevational view of the ceiling fan of the inventionwith its thin edge ceiling fan blades;

FIG. 2 is a transverse cross-sectional view of a conventional MDFceiling fan blade showing the planar construction thereof, the laminatedvinyl material to the opposing surfaces thereof and the waterproofsealant painted onto the leading and trailing edges thereof;

FIG. 3 is a transverse cross-sectional view of FIG. 1 of the thin edgeceiling fan blade of the first embodiment of the invention along lines30-30 thereof as viewed toward the root of the fan blade;

FIG. 4 is a is a transverse cross-sectional view of the secondembodiment of the invention;

FIG. 5 is a transverse cross-sectional view of the third embodiment ofthe invention;

FIG. 6 is a transverse cross-sectional view of the fourth embodiment ofthe invention;

FIG. 7 is a transverse cross-sectional view of the fifth embodiment ofthe invention; and

FIG. 8 is a transverse cross-sectional view of the sixth embodiment ofthe invention as viewed toward the tip of the fan blade.

Similar reference characters refer to similar parts throughout theseveral views of the drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 is a side elevational view of a conventional ceiling fan 10comprising an electric motor assembly 12 and a plurality of ceiling fanblades 14 connected to the rotor of the motor assembly 12 by means ofceiling blade brackets 16. The ceiling fan 10 is intended to beconnected by means of a hanger and down rod assembly 18 to the ceiling20 of a room. During operation in one direction, the rotating ceilingfan blades 14 circulate air downwardly from the ceiling 20 (typicallyduring summer months). During operation in the reverse direction, therotating ceiling fan blades 14 circulate air upwardly toward the ceiling20 (typically during winter months). In either direction, the objectiveis to create a circulatory flow of air throughout the room to therebyreduce energy costs.

FIG. 2 is a cross sectional view of a conventional ceiling fan blade 16manufactured from an MDF material. More particularly, an MDF fan blade16 comprises a generally planar elongated configuration having a width“W” and a thickness “T₁” composed of an MDF laminate 18. Commonly, asheet of a vinyl material 20 is glued to the upper and lower surfaces ofthe MDF material 18. The vinyl material 20 may comprise many differentcolors and/or decorative appearances such as wood grains. Thelongitudinal edges 22 are routed to a bull nose configuration and sandedsmooth. The bull nose rounded longitudinal edges 22 are then sealed bypainting them with a waterproof sealant 24. It is noted that whenemploying plywood instead of MDF, a similar procedure is used to routethe bull nose rounded edges 22 that are then sealed with the sealant 24painted thereon. In the case of plastic fan blades that are injectionmolded, the vinyl material 20 may alternatively comprise a papermaterial which too may comprise a variety of colors or decorativedesigns such as a wood grain.

The many embodiments of the invention are now described in relation toFIGS. 3-8. More particularly, each embodiment of the invention comprisesa ceiling fan blade 30 manufactured by any available manufacturingtechnique such as methods for producing MDF blades, plywood blades,plastic blades or carved blades, to create a generally planar orcurvilinear fan blade 30 having a thickness T₁. At least the thinleading edge 32 and alternatively also the trailing edge 34 comprise areduced thickness T₂ which is appreciably thinner than the thickness T₁of the fan blade 30. The thin leading edge 32 of thickness T₂ morepreferably equals or exceeds the applicable safety standard that definesthe minimum thickness for ceiling fan blades.

As shown in FIGS. 3 and 4, the thin leading edge 32 of the fan blade 30of the invention is positioned in the middle of the thickness T₁ of theblade 30. As shown in FIG. 3, the transition between the thin leadingedge 32 and the opposing surfaces 30U and 30L of the fan blade 30comprises a concave step 36 whereas in FIG. 4, the transition comprisesa generally planar transition 38. In both embodiments of FIGS. 3 and 4,the thin leading edge 32 may be sanded or chamfered to eliminate anysharp corners between the transitions 36 and 38 and the thin leadingedges 32.

As shown in FIGS. 5 and 6, the thin leading edge 32 is positioned closerto the bottom surface 30L of the fan blade 30 rather than beingpositioned midway as shown in the previous embodiments of FIGS. 3 and 4.More particularly, as shown in FIG. 5, the transition between the thinleading edge 32 and the upper surface comprises a stepped configuration40 whereas the transition in FIG. 6 comprises a generally planartransition 42. As in the case of embodiments of FIGS. 3 and 4, the thinleading edges 32 may be sanded or chamfered to break any sharp edgesthat might otherwise occur with the respective transitions 4 and 42.

As noted above, the trailing edge 34 of the ceiling fan blade 30 of theinvention may likewise comprise a thin edge 32 of one of the embodimentsdescribed above. The double thin edge embodiments are particularlyuseful in the event the ceiling fan 10 is operated in a reversedirection whereupon the blades rotate in reverse thus the formertrailing edge becomes a leading edge, and vice versa. Furthermore,without departing from the spirit and scope of the invention, it shouldbe appreciated that one embodiment of the thin leading edge 32 may beused with any of the other embodiments. Finally, it is noted that theembodiments of FIGS. 3 and 4 are the same whether or not the blades areinstalled upside down in reverse whereas the embodiments of FIGS. 5, 6and 7 are not reversible.

As shown in FIG. 7, still another embodiment of the thin edge ceilingfan blade 30 of the invention comprises a generally apex configurationwherein the upper surface 30U of the fan blade comprises two angledsurfaces 30AU extending from opposing thin leading edges 32 and 34 to alongitudinal apex 30A, preferably positioned at or proximate to thelongitudinal center of the fan blade 30.

The longitudinal apex 30A of the fan blade 30 according to thisembodiment produces increased structural integrity along thelongitudinal length of the fan blade 30 to further reduce wobbling ordrooping over time.

The foregoing embodiments of FIGS. 1-6 were shown as generally planarceiling fan blades 14 with its opposing surfaces being generallyparallel to each other. However, as shown in FIG. 8, any of the thinedge embodiments of FIGS. 1-6 may be incorporated into the leading edge32 of curvilinear ceiling fan blades 14 such as those of U.S. Pat. Nos.6,039,541 and 6,659,721, previously incorporated by reference herein.

More particularly, as shown in FIG. 8, a curvilinear ceiling fan blade14 comprises an airfoil 50 composed of an upper surface 50U and a lowersurface 50L that produces a lifting force when rotated. Furthermore, acurvilinear fan blade 14 often comprises an increasing “twist” formedalong its elongated configuration from its tip to its root, such that,preferably, the same volume of airflow is achieved along its entirelength even though the tip of the blade 14 is moving faster than itsroot. The incorporation of the thin leading edge 32 of the inventioninto curvilinear fan blades 14 increases the efficiency by reducingresistance and turbulence.

Without departing form the spirit and scope of this invention, as notedpreviously, the ceiling fan blades 30 may be manufactured from anyavailable technique, with or without vinyl or paper materials on one orboth of the surfaces 30U and 30L thereof and with or without sealing ofthe exposed longitudinal edges 32 and 36-42 thereof.

The present disclosure includes that contained in the appended claims,as well as that of the foregoing description. Although this inventionhas been described in its preferred form with a certain degree ofparticularity, it is understood that the present disclosure of thepreferred form has been made only by way of example and that numerouschanges in the details of construction and the combination andarrangement of parts may be resorted to without departing from thespirit and scope of the invention.

Now that the invention has been described,

1. A ceiling fan comprising in combination: a motor having a rotatablerotor; a plurality of ceiling fans blades having a thickness, saidblades being connected to said rotor to rotate therewith; and each ofsaid ceiling fan blades comprising a thin edge along its leading edgethat is thinner than said thickness of said ceiling fan blade to presentless resistance and produce less turbulence and achieves highefficiencies.
 2. The ceiling fan as set forth in claim 1, wherein saidceiling fan blades each comprises a generally planar elongatedconfiguration.
 3. The ceiling fan as set forth in claim 1, wherein saidceiling fan blades each comprises a generally curvilinear elongatedconfiguration.
 4. The ceiling fan as set forth in claim 1, wherein saidthin edge of each of said ceiling fan blades is at least as great and asan industry standard minimum thickness for leading edges of ceiling fanblades.
 5. The ceiling fan as set forth in claim 1, wherein said thinedge gradually tapers into said thickness of said ceiling fan blade. 6.The ceiling fan as set forth in claim 1, wherein said thin edge stepsinto said thickness of said ceiling fan blade.
 7. The ceiling fan as setforth in claims 5 or 6 wherein said thin edge is centered relative tosaid thickness of said blade.
 8. The ceiling fan as set forth in claims5 or 6 wherein said thin edge is positioned at one surface of said fanblade.
 9. The ceiling fan as set forth in claim 8, wherein said thinedge is position at a lower surface of said fan blade.
 10. The ceilingfan as set forth in claim 1, wherein each fan blade comprises an uppersurface having a generally apex configuration defined by two planarsurfaces formed at an angle leading from the opposing leading edgesacross the width of said fan blade to form an apex along a center lineof the fan blade.
 11. The ceiling fan as set forth in claim 10, whereinsaid thin edge comprises a reduced thickness which is equal to orappreciably greater than the minimum thickness mandated by applicableceiling fan safety regulations.
 12. The ceiling fan as set forth inclaim 1, wherein a trailing edge of each of said ceiling fan bladescomprises a thin edge.
 13. A fan blade comprising a thin leading edgepositioned in the middle of a thickness of the blade.
 14. The fan bladeas set forth in claim 13, wherein a transition area between said thinleading edge and opposing surfaces of said fan blade comprises a concavestep.
 15. The fan blade as set forth in claim 13, wherein a transitionarea between said thin leading edge and opposing surfaces of said fanblade comprises a generally planar transition.
 16. The fan blade as setforth in claims 14 or 15, wherein said thin leading edge is sanded. 17.The fan blade as set forth in claims 14 or 15, wherein said thin leadingedge is chamfered.
 18. The fan blade as set forth in claim 13, whereinsaid thin leading edge is positioned closer to a bottom surface of saidfan blade and wherein a transition area extends between said thinleading edge and an upper surface of said fan blade.
 19. The fan bladeas set forth in claims 14, 15 or 18, wherein said transition areacomprises a stepped configuration.
 20. The fan blade as set forth inclaims 14, 15 or 18, wherein said transition area comprises a generallyplanar transition.
 21. The fan blade as set forth in claim 20, whereinany sharp edges of said thin leading edges are sanded or chamfered. 22.The fan blade as set forth in claim 13, wherein a trailing edgecomprises a thin edge.
 23. The fan blade as set forth in claim 13,comprising a generally apex configuration wherein an upper surface ofsaid fan blade comprises two angled surfaces extending from opposingthin leading edges to a longitudinal apex.
 24. The fan blade as setforth in claim 23, wherein said longitudinal apex is positioned at orproximate to a longitudinal center of the fan blade.
 25. The fan bladeas set forth in claims 13 comprising a generally planar ceiling fanblade with its opposing surfaces being generally parallel to each other.26. The fan blade as set forth in claim 13 comprising a curvilinearceiling fan blade.
 27. The fan blade as set forth in claims 25 or 26,wherein an upper surface and a lower surface of the fan blades producesa lifting force when rotated.
 28. The fan blade as set forth in claims25 or 26, wherein said fan blade comprises an increasing twist formedalong its elongated configuration from its tip to its root.